The dynamic properties of the lipid components of human plasma lipoproteins, the myelin sheath of both peripheral nerves and central nervous system white matter, sarcoplasmic reticulum, the erythrocyte membrane, and the plasma membrane of Mycoplasma are being studied through use of natiral-abundance carbon-13 nuclear magnetic resonance spectroscopy. Emphasis is placed on measurement of spin-lattice relaxation times for selected classes of carbon atoms and on the variation in these as a function of molecular composition and environmental factors. The kinetics of simple organic reactions at the surface of micelles, liposomes, and micelle-forming proteins are under study. Reactions chosen for study include ester and acetal hydrolysis and the addition of nucleophilic reagents to pyridinium ions.